Rack Controller

A rack controller can be connected to multiple VLANs, each from a different
network interface. This provides a scaling factor that can help as a network
architecture grows in size.

Install a rack controller

Installing a rack controller consists of installing the rack controller
software and then registering the rack controller with the region API server.

When a rack controller is installed on the same host as the region API server
registration occurs automatically. This can occur by installing a complete
environment on a single host in one of two ways:

Configuration for multiple API servers

Unregister a rack controller

If you ever want to unregister a rack controller, which is probably something
you would only do to an extra one you may have added, you will need to
delete it from the region API server; there is no 'unregister' command.

To do so, navigate to the 'Controllers' page of the web UI. Enter the
controller's page by clicking on the machine you want to delete and select
'Delete' from the dropdown (and then 'Delete controller'). MAAS will do the
right thing if the controller was used for DHCP HA (i.e. DHCP HA will no longer
be enabled since there is no longer the possibility of having it).

Although similar, this is not conceptually equivalent to deleting a MAAS node.
Here, you are deleting a machine that is a part of MAAS itself.

Note: Unless the software on this machine is removed, rebooting it will cause the machine to re-instate itself as a rack controller. This behaviour may change with future versions of MAAS.

Region/Rack/Machine communication and high-availability environments

Please see Communication for more information about how rack
controllers communicate with region controllers and machines as well as how to
use rack controllers in an HA environment.